The WATCHDOG_* constant definitions correspond to the logging severity levels
defined in RFC 3164, section 4.1.1. PHP supplies predefined LOG_* constants
for use in the syslog() function, but their values on Windows builds do not
correspond to RFC 3164. The associated PHP bug report was closed with the
comment, "And it's also not a bug, as Windows just have less log levels,"
and "So the behavior you're seeing is perfectly normal."